8 Eyes, referred to as 8 Eyes on the North American packaging, is a 2D action platforming video game developed by Thinking Rabbit for the Nintendo Entertainment System. The game features eight levels, and can be played by one or two players. It also features a large, diverse soundtrack, composed by Kenzou Kumei, often quoting from the operatic repertoire, consisting of three pieces for each of the eight levels, each set in a different part of the world.
8 Eyes is set in a post-apocalyptic future. Mankind is recovering from hundreds of years of chaos and nuclear war, and civilization is being rebuilt by the Great King, who harnesses the power of eight jewels. The jewels, known as the 8 Eyes, were formed at the centers of eight nuclear explosions that came close to destroying the Earth. The 8 Eyes have mysterious power which, in the wrong hands, could bring about the end of the world. The Great King's eight power-hungry dukes steal the jewels for themselves and banish the King to the nuclear wastelands, threatening to once again plunge the Earth into war.
The player controls Orin the Falconer and his fighting falcon Cutrus. His mission is to penetrate the Dukes' eight castles and retrieve the 8 Eyes. With the help of Cutrus, you must fight the Dukes' soldiers, nuclear mutants, and the duke of each castle to retrieve the jewels. After the jewels have been recovered, you must return them to the Altar of Peace so that the Great King may return and finish rebuilding the Earth.
The game consists of eight levels, each set in the castle of one of the dukes. At the completion of each level, Orin receives a new sword. The player can choose to play each of the first seven castles in any order, though the boss at the end of each is vulnerable to only one sword. It is therefore easier to play levels in a particular order. There are hints about the correct order hidden throughout the game. Only after each has been completed can the House of Ruth be played.
After the House of Ruth has been cleared and the 8 Eyes recovered, the player must return the jewels to the Altar of Peace. At this point the jewels must be placed in a particular order, or the game is lost. Hints about the order of the jewels are also hidden throughout the game.
8 Eye's features a cooperative mode in which one player controls Orin and the other player controls Cutrus. In the single-player mode, the player has limited control of both characters simultaneously, making the game significantly more difficult.
The gameplay and graphical style are noticeably similar to Castlevania.